Conventionally, batteries (so-called secondary cells) have been used as a power supply source in electric vehicles. The battery needs to be charged with the required power by the time of use. In view of this, Patent Literature 1 discusses a charging control device that adjusts the battery charging speed and charge amount according to information such as the remaining capacity of the battery, the destination of the next trip, and the scheduled departure time on the next trip. The invention discussed in Patent Literature 1 assumes a case in which a single battery is used for one user.
Recent years have seen the advent of a system for loaning out a plurality of batteries to users of electric cars. This system is called a battery swap system because it exchanges (swaps) a returned battery with a charged battery when the used battery is returned from the user of the system (see Patent Literature 2, for example).